Scalable media access control for multi-hop high bandwidth communications

ABSTRACT

A scalable medium access control (“MAC”) module is provided that avoids conflict resource reservation so that network performance does not degrade as the number of hops or nodes in a wireless network increases. The MAC also provides different access schemes for traffic with different quality of service (“QoS”) requirements such that QoS is guaranteed and network resources are efficiently utilized. Furthermore, the resource allocation scheme determines the routing path as resources is allocated for data traffice, thereby achieving more robust layer-2 routing at the MAC layer. Finally, the scalable MAC is compliant with both WiMedia MAC and IEEE 802.15.3 MAC.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a Continuation of U.S. application Ser. No.14/090,760, filed Nov. 26, 2013, which is a Continuation of U.S.application Ser. No. 12/950,558, filed Nov. 19, 2010, which is aDivisional of U.S. application Ser. No. 11/462,663, filed Aug. 4, 2006,which is a Continuation-in-Part of U.S. application Ser. No. 10/816,481,filed Apr. 1, 2004, which is a Continuation-in-Part of U.S. applicationSer. Nos. 10/437,128 and 10/437,129 filed May 13, 2003, which both claimthe benefit of U.S. Provisional 60/380,425, filed May 13, 2002; and U.S.application Ser. No. 11/462,663 is a Continuation-in-Part of U.S.application Ser. No. 11/076,738 filed Mar. 9, 2005, which is aContinuation-in-Part of U.S. application Ser. No. 10/816,481, filed Apr.1, 2004, which is a Continuation-in-Part of U.S. application Ser. Nos.10/437,128 and 10/437,129 filed May 13, 2003, which both claim thebenefit of U.S. Provisional 60/380,425, filed May 13, 2002; U.S.application Ser. No. 11/076,738 is also a Continuation-in-Part of U.S.application Ser. Nos. 10/437,128 and 10/437,129, filed May 13, 2003,which both claim the benefit of U.S. Provisional 60/380,425, filed May13, 2002; U.S. application Ser. No. 11/462,663 is a Continuation-in-Partof U.S. application Ser. No. 11/420,668, filed on May 26, 2006, whichclaims the benefit of U.S. Provisional 60/747,409, filed May 16, 2006,and U.S. application Ser. No. 11/420,668 is a Continuation-in-Part ofU.S. application Ser. No. 11/076,738 filed Mar. 9, 2005, which is aContinuation-in-Part of U.S. application Ser. No. 10/816,481, filed Apr.1, 2004, which is a Continuation-in-Part of U.S. application Ser. Nos.10/437,128 and 10/437,129, filed May 13 2013, which both claim thebenefit of U.S. Provisional 60/380,425; U.S. application Ser. No.11/076,738 is also a Continuation-in-Part of U.S. application Ser. Nos.10/437,128 and 10/437,129, filed May 13 2013, which both claim thebenefit of U.S. Provisional 60/380,425, filed May 13, 2002, each ofwhich is incorporated herein by reference in its entirety.

BACKGROUND

The present disclosure is generally related to wireless communicationsand more particularly related to a scalable medium access control(“MAC”) module for use in multi-hop wireless network communications overhigh bandwidth wireless communication channels based on ultra-wide band(“UWB”) or orthogonal frequency division multiplexing (“OFDM”) amongothers.

RELATED ART

In recent times, UWB technology has gone through significant progress.Many different competing proposals for UWB networking have beenconsolidated into two major camps. The first proposal falls under theWiMedia umbrella and is backed by companies including Intel, Microsoft,and Phillips, among others. The second proposal falls under the UWBForum umbrella and is backed by Motorola, Freescale, among othercompanies.

UWB communication technologies hold out the promise of high speedtransmission rates over short distances. However, to extend the coverageof UWB networks without compromising the high speed transmission rates,a wireless mesh network is needed. Additionally, by using meshnetworking to extend UWB coverage, the network reliability and faulttolerance of UWB networks can advantageously be improved.

The conventional medium access control (“MAC”) protocols of UWBnetworks, in particular, IEEE 802.15.3 MAC and WiMedia MAC (includingthe multi-band OFDM alliance (“MBOA”) MAC) can also support meshnetworking, the performance of these conventional MAC solutions lacksscalability in a multi-hop mesh network environment.

Additionally, no single UWB communication solution has taken hold in theindustry. For example, the physical layer of WiMedia is based on theMBOA (“MBOA-UWB”) or multi-band OFDM UWB while the physical layer of theUWB Forum is based on direct sequence UWB (“DS-UWB”). The majordifference between MBOA-UWB and DS-UWB is that MBOA-UWB splits theentire UWB spectrum into several bands during which orthogonal frequencydivision multiplexing (“OFDM”) is used.

In addition to these physical layer differences, the MAC layer is alsodifferent for these competing UWB technologies. The WiMedia MAC, asdefined in ECMA-368 [1], consists of both CSMA/CA in the prioritizedcontention access (“PCA”) period and time division multiple access(“TDMA”) in the contention free period. A superframe in the MAC definedby the UWB Forum, as specified in IEEE 802.15.3 [2], consists of acontention access period (“CAP”) and channel time allocation period(“CTAP”). In CAP, CSMA/CA is used, while slotted Aloha and TDMA are usedin the CTAP.

Another major difference in the MAC of these two proposals lies in theformation of their respective network topologies. Under the IEEE802.15.3 approach, nodes within communication range of each other areorganized into a piconet, which is managed under a piconet coordinator(“PNC”). The disadvantage of this approach is that no specification isavailable for multi-hop networks.

In contrast, under the WiMedia approach, nodes using the same beaconperiod (“BP”) are organized into a single distributed peer-to-peernetwork and the WiMedia MAC uses a fully distributed protocol with nocentral point of control or coordinator. When two networks withdifferent BPs come within range of each other, merging of the BPs isnecessary. Once this is done, the individual peer-to-peer networksbecome a multi-hop distributed network.

Although both the IEEE 802.15.3 MAC and the WiMedia MAC can be extendedto support multi-hop wireless networking among devices, the performanceof these types of multi-hop networks is not scalable and fails toachieve some of the primary goals of wireless mesh networking.

Specifically, under the IEEE 802.15.3 MAC approach, there is no solutionfor internetworking of piconets. Thus, the IEEE 802.15.3 completelyfails to describe how a mesh network can be formed from piconets. As aresult, no multi-hop performance information is provided either.

Additionally, under the IEEE 802.15.3 MAC approach, no resourceallocation for a mesh network is even contemplated. The describedallocation scheme for piconet is not applicable to a multi-hop meshnetwork.

Finally, under the IEEE 802.15.3 MAC approach, an individual piconet isunder centralized control of the PNC. One significant drawback of thisscheme is that when a network size is large, this scheme is not scalableand easily fails. Although the centralized control of the PNC can bepassed from one node to another, such passing causes a significantamount of overhead and proves to be too slow to meet the requirements ofhigh speed networking.

Under the WiMedia MAC approach, a mesh network is formed by mergingdifferent groups of peer-to-peer networks with different BPs. However,resource allocation between groups being merged can be in conflict. Theresulting requirement of resolving such conflicts also proves to be tooslow and non-convergent.

Additionally, under the WiMedia MAC approach, distributed resourceallocation is only carried out locally and no end-to-end resourceallocation solution is contemplated. As a result, there is a significantincrease in communication errors because the routing protocol mayunknowingly select a routing path without enough resources. Therefore,what is needed is a system and method that overcomes these significantproblems found in the conventional systems as described above.

SUMMARY

Accordingly, described herein are systems and methods employing animproved MAC that avoids conflict resource reservation so that thenetwork performance will not degrade as the number of hops or nodesincreases. The scalable MAC also provides different access schemes fortraffic flows with different quality of service (“QoS”) requirementssuch that QoS is guaranteed and network resources are efficientlyutilized. Additionally, a resource allocation scheme is provided andemployed by the MAC that dynamically determines the routing path asresources are allocated for data traffic, resulting in more robustcommunications due to layer-2 routing being incorporated into the MACprotocol. Finally, the scalable MAC is compliant with both WiMedia MACand IEEE 802.15.3 MAC to allow for seamless adoption by the industry.

The MAC is scalable because the resource allocation scheme isdistributed and achieves high channel spatial-reuse efficiency withoutconflict allocation and because the resource allocation is performedtogether with routing which achieves layer-2 routing within the MACprotocol and thereby ensures optimal performance in both routing and theMAC layer. Additionally, the resource allocation scheme improves QoSsupport for traffic requiring a certain level of reliability such asreal-time multimedia.

Other features and advantages of the present invention will become morereadily apparent to those of ordinary skill in the art after reviewingthe following detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The details of the present invention, both as to its structure andoperation, may be gleaned in part by study of the accompanying drawings,in which like reference numerals refer to like parts, and in which:

FIG. 1 is a network diagram illustrating an example wireless networkwith a mesh topology according to an embodiment of the presentinvention;

FIG. 2 is a network diagram illustrating an example wireless networkwith a piconet topology according to an embodiment of the presentinvention;

FIG. 3 is a network diagram illustrating an example wireless networkwith a hybrid topology according to an embodiment of the presentinvention;

FIG. 4 is a block diagram illustrating an example neighbor listaccording to an embodiment of the present invention;

FIG. 5 is a block diagram illustrating an example MAC protocolsuperframe according to an embodiment of the present invention;

FIG. 6 is a block diagram illustrating an example wireless communicationdevice according to an embodiment of the present invention;

FIG. 7 is a block diagram illustrating an example topology moduleaccording to an embodiment of the present invention;

FIG. 8 is a block diagram illustrating an example layer-2 signalingmodule according to an embodiment of the present invention;

FIG. 9 is a block diagram illustrating an example resource allocationmodule according to an embodiment of the present invention;

FIG. 10 is a flow diagram illustrating an example process forinitializing communications in a wireless network according to anembodiment of the present invention;

FIG. 11 is a flow diagram illustrating an example process foridentifying the topology of a wireless network according to anembodiment of the present invention;

FIG. 12 is a flow diagram illustrating an example process for allocatinginitial timeslots in a wireless network according to an embodiment ofthe present invention;

FIG. 13 is a flow diagram illustrating an example process for allocatingresources for best effort wireless communication according to anembodiment of the present invention;

FIG. 14 is a flow diagram illustrating an example process for allocatingresources for reliable transmission according to an embodiment of thepresent invention;

FIG. 15 is a flow diagram illustrating an example process for resourcereservation according to an embodiment of the present invention;

FIG. 16 is a block diagram illustrating an example wirelesscommunication device that may be used in connection with variousembodiments described herein; and

FIG. 17 is a block diagram illustrating an example computer system thatmay be used in connection with various embodiments described herein.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Certain embodiments as disclosed herein provide for a MAC module that isconfigured to be deployed in a wireless communication device tofacilitate multi-hop wireless network communications over high bandwidthwireless communication channels based on UWB, OFDM, 802.11/a/b/g, amongothers. In one embodiment, the nodes involved in the multi-hop wirelesscommunications are arranged in a mesh network topology. For example, onemethod as disclosed herein allows for the MAC module to determine thenetwork topology by parsing beacon signals received from neighbor nodeswithin communication range and establish high bandwidth communicationlinks with those nodes that are within range to provide a signal qualitythat supports high bandwidth communication. For applications thatrequire a certain level of quality of service, the methods hereinprovide for establishing a multi-hop end-to-end route over the meshnetwork where each link in the route provides the necessary level ofsignal quality.

After reading this description it will become apparent to one skilled inthe art how to implement the invention in various alternativeembodiments and alternative applications. To facilitate a directexplanation of the invention, the present description will focus on anembodiment where communication is carried out over a UWB network,although the invention may be applied in alternative networks including802.11, 802.15, 802.16, worldwide interoperability for microwave access(“WiMAX”) network, wireless fidelity (“WiFi”) network, wireless cellularnetwork (e.g., wireless wide area network (“WAN”), Piconet, ZigBee, IUPmultimedia subsystem (“IMS”), unlicensed module access (“DMA”), genericaccess network (“GAN”), and/or any other wireless communication networktopology or protocol. Additionally, the described embodiment will alsofocus on a single radio embodiment although multi-radio embodiments andother multiple input multiple output (“MIMO”) embodiments are certainlycontemplated by the broad scope of the present invention. Therefore, itshould be understood that the embodiment described herein is presentedby way of example only, and not limitation. As such, this detaileddescription should not be construed to limit the scope or breadth of thepresent invention as set forth in the appended claims.

FIG. 1 is a network diagram illustrating an example wireless network 10with a mesh topology according to an embodiment of the presentinvention. In the illustrated embodiment, the network 10 comprises fourwireless communication device (also referred to herein as “nodes”),namely devices 20, 30, 40, and 50. Each node is configured with a datastorage area, namely data storage areas 22, 32, 42, and 52. Each of thedevices is in wireless communication range with one or more otherdevices in the network 10.

The network 10 can be a personal area network (“PAN”), local areanetwork (“LAN”), wide area network (“WAN”), or a distributed combinationof networks collectively comprising a global communications network suchas the Internet. Network 10 can be fixed in location, mobile, or maycomprise a combination of fixed and mobile components. Additionally,network 10 may carry communications corresponding to a single networkprotocol or to multiple network protocols. For example, network 10 maybe a UWB network for carrying high bandwidth wireless traffic. In oneembodiment, the network 10 may be a UWB network organized in apeer-to-peer topology, a star network topology, a mesh network topology,a piconet topology, or any other sort of network topology. Additionally,the network 10 may periodically and dynamically change from one topologyto another topology as wireless nodes change relative locations. In analternative embodiment, the network 10 may also be a wired network.

Furthermore, the network 10 may be employed to implement any of avariety of applications. Advantageously, the network 10 is configurablefor high bandwidth traffic so the types of applications that can runover the network 10 are not limited and include, for example,applications such as: data, voice, video, triple-play, multimedia, highdefinition video, VOIP, video conferencing, video games, multi-playervideo games with piggy-backed VOIP, general internet browsing, andclient-server applications, just to name a few.

In this detailed description, a wireless communication device such asdevice 20 may also be referred to as a network device, device, networknode, node, wireless device, or wireless node. Although various namesmay be used herein, a wireless device may comprise all or a minimalsubset of the components and functional capabilities described herein,fore example those features described with respect to FIGS. 6-9, 16 and17.

Notably, the wireless communication devices such as device 20 can be anyof a variety of wireless communication devices including but not limitedto a laptop computer, cell phone, personal digital assistant (“PDA”),game console, wireless TV set and set-top box, radio frequencyidentification (RFID) device, or any of a variety of stationary ormobile devices with which communication is desirable.

Additionally illustrated in FIG. 1 are several wireless communicationlinks (not labeled) between the various nodes. In one embodiment, aplurality of links together comprise a path between the two terminalnodes.

FIG. 2 is a network diagram illustrating an example wireless network 15with a piconet topology according to an embodiment of the presentinvention. In the illustrated embodiment, the piconet 15 comprises nodes25, 35, 45, and 55. Each node is configured with a data storage area,namely data storage areas 27, 37, 47, and 57. As will be understood bythose having skill in the art, node 25 is considered the piconetcontroller (“PNC”) and is responsible for maintaining communicationsbetween all of the nodes in the network 15. In one embodiment, thepiconet 15 operates in accordance with the IEEE 802.15.3 standard andmay employ Bluetooth or other communication links between the variousnodes in the piconet 15.

FIG. 3 is a network diagram illustrating an example wireless network 100with a hybrid topology according to an embodiment of the presentinvention. In the illustrated embodiment, the network 100 comprises amesh network 102 between nodes 110, 120, and 130. These nodescooperatively communicate with each other and various other nodes toprovide a dynamic wireless communication network 100 that enables eachnode to communicate directly or indirectly with each other.

Additionally, the illustrated embodiment comprises piconet networks 104,106, and 108. Piconet 102 comprises nodes 110 as the PNC and nodes 112,114, and 116. Similarly, the PNC for piconet 106 is node 130 and itsother member nodes are 132, 134, and 136. The PNC for piconet 108 isnode 120 and its other member nodes are 122, 124, and 126. Although notshown, each node in the figure can be configured with a data storagearea.

Also illustrated are optional communication links 150 that providedirect communication between member nodes of different piconets.Although not shown in FIG. 3, there may be multi-hop routes betweennodes that are in a single piconet. For example, a node 113 (notillustrated) may be in communication solely with node 112 and thereby beincluded in piconet 104 and accessible via a communication pathincluding more than one hop.

In alternative embodiments, disparate network topologies other thanpiconets and mesh networks may be merged into a single wireless networksuch as network 100. Advantageously, the nodes in these disparatetopologies can employ the MAC module described herein to facilitate highbandwidth communications by forming a mesh network or employing thecommunication capabilities of the MAC module within existing topologies.

In an alternative embodiment, nodes using different broadband wirelesscommunication technologies may be merged into a single wireless networksuch as network 100. For example, node 112 may be a UWB device, node 122may be a WiFi device, and node 132 may be a WiMAX device. It isanticipated that such different wireless communication technologies willoverlap in their use of frequency in the future and as such, variousnodes employing different technologies may cause interference with eachother. Accordingly, integrating the various nodes using differenttechnologies into a single network 100 precludes frequency interferenceby providing a common communication framework over the variousfrequencies, channels, and timeslots employed the various devices. Thesingle network 100 additionally provides the advantage of allowing allof the nodes using different broadband wireless communicationtechnologies to communicate with each other.

For example, UWB radios are expected to use all frequency bands from 3.1GHz up to 10 GHz. These frequency bands overlap with the frequency bandsused by WiFi radios and WiMAX radios. Advantageously, the single network100 allows nodes employing a diverse set of broadband wirelessnetworking technologies to coexist and communicate with each other,successfully meeting the needs of different users and differentapplications. In one embodiment, nodes 110, 120, and 130 in the hybridnetwork 100 provide a bridging capability between the different wirelesscommunication technologies through a separate interface for each, suchas UWB, WiFi, and WiMAX. Accordingly, a multi-hop path can be formedusing WiFi links, UWB links, WiMAX links, or any combination of theseand other communication links. Advantageously, the scalable MAC moduleon each node employs layer-2 routing to identify the appropriatecommunication technology for each link and uses that as a parameter orproperty for the link to form a hybrid path that satisfies the QoSrequirements of the end-to-end nodes that are in communication with eachother, whether using best effort traffic or reliable transmissiontraffic.

In yet another embodiment, the network 100 comprises networks 102, 104,106, and 108 and each of these networks is a discrete network. Forexample, network 104 may be a wireless WAN operated by a carrier whilenetwork 106 is a wireless LAN in a home environment. Advantageously, thescalable MAC module allows node 132 to communicate directly with node114 if the two nodes are in proximity of each other.

Additionally, node 132 can be a mobile device and thereby when it movesfrom one location to another the scalable MAC allows node 132 to roambetween the wireless LAN 106 and the wireless WAN 104. The roamingbetween network 106 and network 104 may be accomplished throughbeaconing with a node in network 104 when node 132 comes into proximitywith such a node. The roaming between network 106 and network 104 mayalso be accomplished through communications with node 110. For example,the network 104 may have an access point topology where each node in thenetwork 104 communicates through the node 110. Such dynamic switchingbetween wireless networks is advantageously facilitated by the scalableMAC module and its use of beaconing to identify its network topology andneighbor list and can be employed between networks with no centralizedcontroller (such as two mesh networks) or networks with a centralizedcontroller (such as a piconet), or any combination of networks with orwithout a centralized controller.

FIG. 4 is a block diagram illustrating an example neighbor listaccording to an embodiment of the present invention. Advantageously, anode in a mesh network may maintain a routing table of nodes that it isaware of. The routing table preferably contains useful information suchas the number of hops to reach the destination node, the very next hopin the path to reach the destination node, a preferred communicationchannel for the destination node, and a power level for the destinationnode. The power level preferably indicates the power level at which tobroadcast packets when initiating communications with the recipientnode. Additional information may also be included in the neighbor list,for example the signal-to-noise ratio (“SNR”), the signal strength, andother useful information.

In one embodiment, as nodes join a network such as network 100 shown inFIG. 3, the nodes receive beacon signals from the other nodes in thenetwork. A new node can parse the beacon signals and populate itsneighbor list accordingly. For example, all of the nodes that send abeacon signal are considered to be neighbor nodes because their beaconsignals are within range of the new node. However, some beacon signalsthat are received may be discarded if the signal strength of the beaconis too low to support high bandwidth communications, for example, UWBcommunications.

FIG. 5 is a block diagram illustrating an example MAC protocolsuperframe 200 according to an embodiment of the present invention. Inthe illustrated embodiment, the superframe 200 comprises a beacon period(“BP”) 210, contention access period (“CAP”) 220, and a contention freeperiod (“CFP”) 230. The portions of the superframe 200 are shown asdivided up into a plurality of timeslots. In one embodiment, the numberof timeslots in each period is adjustable and controlled by the scalablemulti-hop MAC module. Additionally, the length of each individualtimeslot can depend on whether the underlying radio is WiMedia or IEEE802.15.3 based.

One advantage of arranging the superframe into the BP, CAP, and CFP isthat this organization is also followed by both the WiMedia MAC and theIEEE 802.15.3 MAC. For example, the superframe 200 allows the use ofcarrier sense multiple access/collision avoidance (“CSMA/CA”) in the CAPcombined with the use of TDMA in the CFP. Because the CAP uses CSMA/CA,it is compatible with both WiMedia and IEEE 802.15.3 and the periods canbe easily aligned since period timing information is provided in thebeacon signals which are analyzed by the scalable MAC module.

Additionally, during the CFP, in order to avoid collisions with nodesemploying WiMedia or IEEE 802.15.3, connection setup or tear downmessages follow the packet formats defined in WiMedia or IEEE 802.15.3MAC so that nodes using WiMedia or IEEE 802.15.3 MACs are made aware ofthe timeslot allocation for nodes using the scalable MAC module and viceversa. Thus, when no timeslot conflicts are present, nodes using thepresently described scalable MAC module can communicate with bothWiMedia nodes and IEEE 802.15.3 nodes in a UWB or other high bandwidthnetwork.

During the beacon period, signaling messages are passed around among thenodes in the wireless network. Each node sends a beacon signal duringthis period so that new nodes joining the network can identify the setof neighbor nodes. The beacon signal includes information about thesender node as well as information from its own neighbor list tofacilitate the propagation of network topology information to all nodesin the network.

During the contention access period, the nodes in the networkcollaboratively assign timeslots for communication during the contentionfree period and identify routes where necessary for reliable end-to-endcommunications. The assignment of timeslots amongst the nodes is done inan interleaved fashion in order to optimize the use of spectrum amongstall nodes in the network and ensure the highest throughput and qualityof service.

During the contention free period, the nodes in the network send andreceive data communications during the various timeslots under a TDMAparadigm.

FIG. 6 is a block diagram illustrating an example wireless communicationdevice 20 according to an embodiment of the present invention. In theillustrated embodiment, the node 20 comprises a topology module 250, alayer-2 signaling module 260, and a resource allocation module 270. Aspreviously described, the node 20 can be any sort of wirelesscommunication device.

In one embodiment, the various modules shown in the figure can beincorporated into a MAC module that implements layer-2 communications ona wireless network. Advantageously, the MAC module is scalable becausethe network topology is formed with links having the best link quality.Accordingly, adding new nodes with high quality links does not introducedecreased performance levels to the network. Additionally, distributedTDMA is guaranteed to have no conflict of resource allocation andlayer-2 routing is incorporated into the resource allocation process forboth best effort and reliable transmission traffic. Advantageously, theMAC module can be implemented in software for deployment onoff-the-shelf UWB chipsets or it can be embedded into the MAC sublayerof the UWB chipsets such that the UWB chipsets are shipped withmesh-ready functionality.

The topology module 250 is configured to align the node's beacon signalwith the mesh network. In one embodiment, when a UWB node joins a meshnetwork, the topology module 250 accomplishes alignment of the node'sbeacon signal with the mesh network by receiving and analyzing beaconsignals from other nodes within wireless communication range anddeveloping and maintaining a neighbor list that describes the currenttopology of the wireless network. For example, during the beacon period,the topology module 250 may receive five beacon signals. Of the five,perhaps only four are received with sufficient signal quality to beconsidered a neighbor node. Accordingly, each of the four beacon signalsare analyzed by the topology module 250 to identify who the sender nodeis, what the signal quality is, who the sender node's neighbors are, andother useful information for determining the topology of the wirelessnetwork.

One aspect of determining the topology can be described with referenceto the discarded fifth beacon signal described above. Since the sendernode of that beacon signal is not a direct neighbor, one or more of thefour beacon signals with sufficient quality may include the sender ofthe discarded fifth beacon signal as a neighbor. In such a case, theneighbor list can include the sender of the fifth beacon signal as amulti-hop neighbor with a path (i.e., the node(s) through whichcommunications for the sender of the fifth beacon signal should go) thatincludes the neighbor with the highest signal strength between it andthe sender of the fifth beacon signal. In this fashion, the topologymodule 250 can identify the various direct and multi-hop nodes withincommunication range to determine the topology of the wireless networksuch that high quality high bandwidth communications may take place.

The layer-2 signaling module 260 is configured to send and receive MAClayer control and signaling messages. The layer-2 signaling module 260also implements optional layer-2 routing. Advantageously, layer-2signaling and control messages are sent and received in the timeslots inthe initial allocation and unicast signaling between nodes is employedby the layer-2 signaling module 260 in order to increase the reliabilityof signaling and delivery of control messages.

The resource allocation module 270 is configured manage routing for besteffort traffic and reliable transmission traffic. In one embodiment,reliable transmission traffic includes data for multimedia applications,for example, audio and video data. Because there are no QoSspecifications for best effort traffic, the resource allocation module270 establishes an end-to-end traffic flow as needed for such traffic.This can be accomplished by setting up a routing path in the MAC layer(i.e., layer-2). Advantageously, resource sharing within neighboringnodes is implemented during resource allocation to provide fair queuingand delivery of best effort traffic.

For reliable transmission traffic, the resource allocation module 270identifies the QoS requirements and delivery specifications for suchtraffic and identifies and establishes an end-to-end traffic route forsuch data. To accomplish this end-to-end route, an admission controlprocess is employed by the resource allocation module 270 to setup ahigh bandwidth route with sufficient resources allocated to each link inthe route. Accordingly, resource allocation is determined when the routeis established. Once the route is successfully established, theconnection is admitted and data traffic may proceed. If no acceptableroute can be established with adequate resources, the route is denied.

FIG. 7 is a block diagram illustrating an example topology module 250according to an embodiment of the present invention. In the illustratedembodiment, the topology module 250 comprises a beacon module 252 and atimeslot module 254.

The beacon module 252 is configured to send and receive beacon signalsand form the wireless network topology based on information received inthe beacon signals from other UWB nodes in the network. Advantageously,the fields and format of the beacon signal can be enhanced to provideadditional data that is useful in forming the network topology withoutintroducing any compatibility issues with WiMedia or IEEE 802.15.3nodes. For example, neighbor node information can be included in thebeacon signal as well as signal strength, SNR information, and otheruseful data.

In one embodiment, when identifying the topology of the network, thebeacon module determines the list of neighbor nodes, establishes areliable high transmission link with each neighbor node, and acquiressynchronization with the neighbor nodes. All of these tasks areadvantageously performed through beaconing. For example, when a new UWBnode joins a network, it receives one or more beacons and checks thesignal quality of each. The node sending the beacon signal is added tothe neighbor list of the new UWB node and the link quality is examinedto determine if a reliable high transmission link can be established.Because the transmission rate in UWB communications is very sensitive tothe distance between nodes (and thus the signal strength between nodes)only those links with the highest transmission rate will be set up toensure the best quality. Otherwise stated, communication between nodesthat are too far away or do not have reliable links is carried out bymulti-hop mesh networking to deliver packets. It should be noted that,although a link between two nodes is setup with the highest transmissionrate, its actual transmission rate may vary depending on theenvironmental conditions at the time of transmission.

In parallel with building the neighbor list and setting up the link, thenew node also acquires synchronization information from the network.This information is obtained from the beacon messages. Thesynchronization information allows the beacon module to align thesuperframe of the new node with the superframe of the other nodes in thenetwork. The synchronization information also allows the beacon moduleto align the beacon period, the contention access period, and thecontention free period.

The timeslot module 254 is configured to allocate initial timeslots andinterleaved timeslots in the contention free period for the new node.Advantageously, the allocation of initial timeslots allows a new nodethe resources to send packets prior to the actual allocation ofinterleaved timeslots in the contention free period. Note that beforeinitial timeslot allocation is done, the new node has to send itsinformation by piggybacking information in a beacon message or sendinginformation during the CAP using unreliable CSMA/CA.

The allocation of initial timeslots is particularly important whenadmission control is needed to establish a reliable transmission routefor high QoS traffic, for example with multimedia applications. Theallocation of initial timeslots also allows a new node to send reliablesignaling messages including MAC and routing related messages.Additionally, the allocation of initial timeslots allows a new node toassist with the interleaving of timeslots allocated to it.

For example, in TDMA if a consecutive block of timeslots are allocatedto a single node, the throughput performance may suffer in a multi-hopnetwork. Accordingly, timeslot module 254 is configured to allocatetimeslots in an interleaved fashion. To achieve this, the initialtimeslots of each node are uniformly distributed in the entire CFP ofthe superframe. Later, when more timeslots are allocated by thedistributed allocation scheme, they can advantageously be selected fromthe timeslots that immediately following the initial timeslots.

The timeslot module 254 is configured to obtain initial timeslots forthe new node that are not in conflict with the timeslots of the othernodes in the network and that are uniformly distributed in the CFP ofthe superframe. For example, if the number of the initial timeslots foreach node is N. In one embodiment, the number of initial timeslots maybe implemented as a modifiable system parameter. The number N can alsobe dynamically determined by assuming that the block size of timeslots(the maximum number of consecutive timeslots allocated to each node) isM; the maximum number of neighbors in the network is K, and totaltimeslots in the CFP is T, then N=T/(MK).

Once the number of initial timeslots N has been determined, the timeslotmodule 254 next determines where these initial timeslots can be placedin the CFP for uniform distribution. To determine how best to uniformlydistribute the initial timeslots, the new node collects information fromneighboring nodes that are up to two-hops away. This information isobtained through beaconing. Based on the collected information, the newnode identifies what timeslots have been allocated to its neighbors andselects its initial timeslots from the remaining free timeslots in theCFP. This provides for the initial allocation. The selection processadvantageously chooses timeslots that are evenly spaced from each otherand separated by other nodes' initial timeslots in order to achieveinterleaving and thereby optimal throughput. After the initial timeslotsare selected, the new node informs its neighbors within two hops of itsreservation of those timeslots. Advantageously, the messages sent toinform neighboring nodes can be sent in the next available initialtimeslot. This also provides other new nodes with the timeslotreservation information in order to reduce any conflicts during initialtimeslot allocation.

The timeslot module 254 is additionally configured to select timeslotsduring distributed timeslot allocation for best effort traffic orreliable transmission traffic. As explained before, the initialtimeslots are the reference point for selecting additional timeslots inthe CFP. In one embodiment, when additional timeslots are allocated to anode, they are selected from the blocks of timeslots following thenode's initial timeslots. Since the allocation of initial timeslots isbased on topology (e.g., the number of nodes in the network) the numberof initial timeslots per node is not optimally distributed—especiallywhen the various nodes have an unbalanced traffic load. For example, onenode may have a significant amount of traffic to send while another nodemay have a very low traffic load. In such a scenario, the high trafficnode needs to be assigned more of the timeslots in the CFP. If theblocks of timeslots following the node's initial timeslots do not meetthis need, then some of the timeslots assigned to this node can beselected in the blocks of timeslots following other nodes' initialtimeslots.

Advantageously, the timeslot module 254 first allocates additionaltimeslots to a node that all in the blocks that follow the node'sinitial timeslots because this is most efficient. If additionaltimeslots are needed, then these timeslots can be reserved from blocksthat follow other nodes' initial timeslots.

FIG. 8 is a block diagram illustrating an example layer-2 signalingmodule 260 according to an embodiment of the present invention. In theillustrated embodiment, the signaling module 260 comprises a messagingmodule 262 and a routing module 264. In one embodiment, the messagingmodule 262 is configured to handle layer-2 signaling during the initialtimeslots, which are those timeslots in the CAP and are allocated suchthat there is no conflict between transmitting nodes. Thus, signalingmessages are sent out with a very high probability of successfuldelivery. However, because wireless channel errors may still occur, areliable mechanism is still needed for signaling so that the performanceof the layer-2 MAC module is not compromised by unreliable transmissionof signaling messages.

In order to accomplish reliable transmission of signaling messages,unicast transmission of signaling messages is implemented by themessaging module 262. For example, when a node needs to send a signalingmessage to all of its neighbors the messaging module 262 sends themessage to each neighbor, one by one, using a unicast message withacknowledgement procedure. While this may appear to increase traffic andintroduce delays, the overall effect is actually faster communicationbecause the reliability is guaranteed and less retries are required, forexample, when channel quality is poor.

The routing module 264 is configured to identify layer-2 routes for besteffort traffic and establish layer-2 routes for reliable transmissiontraffic. Although the MAC module includes the routing module 264, whichis configured to implement layer-2 routing, this layer-2 routing can beturned off as needed. Therefore, it is optional. When layer-2 routing isdisabled, the MAC module behaves the same for best effort traffic exceptthat the routing path is setup by the layer 3 routing. Additionally,when layer-2 routing is disabled, the establishing of an end-to-endreliable transmission (admission control), for example for multimediatraffic, is carried out at layer 3. One disadvantage of this is that theroute established by layer 3 will likely not provide optimal performancesince it is not tied in with resource allocation during setup of theroute.

FIG. 9 is a block diagram illustrating an example resource allocationmodule 270 according to an embodiment of the present invention. In theillustrated embodiment, the resource allocation module 270 comprises arouting path module 272, a best effort traffic module 274, and areliable transmission traffic module 276.

The routing path module 272 works in cooperation with the best efforttraffic module 274 and the reliable traffic module 276 in order toprovide on demand routes for best effort traffic and establishedend-to-end routes for reliable transmission traffic.

The best effort traffic module 274 finds the best routing path on demandfor new best effort traffic and performs fair queuing for all besteffort traffic flows in each group of neighboring nodes. For example,for best effort data traffic there is no QoS or traffic specificationinformation available for the best effort traffic module 274 to carryout the resource allocation. Thus, there is no need to reserve anytimeslots for best effort traffic. Resource allocation for best efforttraffic is therefore carried out on demand for all traffic flows ratherthan per flow.

Once a new traffic flow starts, the best effort traffic module 274instructs the routing path module 272 to determine the routing path fromend to end. In one embodiment, the optimal end to end route can bedetermined based on minimum hop count and the load of each link Notethat link quality does not need to be considered because the previouslydescribed topology module operates to ensure that each link is the bestavailable when it is established. Advantageously, excluding link qualityfrom the routing metrics allows the routing path to be setup with higherstability. And additional advantage of considering the traffic load oneach link when determining the routing path is that this inherentlyprovides load balancing across the UWB network.

Additionally, the use of layer-2 routing improves performance becauseall of the signaling messages related to routing are initiated, sent,received, and processed at the MAC layer. Furthermore, because theinitial timeslots for reliable layer-2 signaling are reserved, therouting related messages can be sent and received more quickly andreliably, which greatly improves the overall efficiency of the routingprotocol, particularly in a multi-hop mesh network environment.

When an on demand routing path is set up, even if load balancing isconsidered the actual traffic load on each link is not proportional tothe number of timeslots allocated to the link The traffic load on eachlink varies depending on the fluctuation of traffic patterns ondifferent flows. Thus, considering any given link on the routing path,its assigned timeslots may not be enough to handle the required trafficload for a particular flow. Accordingly, the resource allocation module270 employs a fair resource allocation process that periodically adjuststhe resource allocation on each node in the network. In on embodiment,this process is triggered by one node in the network and duringexecution is passed from one node to the next node when the previousnode is done.

During fair resource allocation, at each node the traffic load of besteffort traffic to different destinations is estimated and the trafficload and timeslots are compared for different links from this node toits neighbors. The timeslots that are more than the traffic load arethen released and reassigned to those links with insufficient timeslots.This adjustment takes place across all nodes in the network so that thebest effort traffic resources are fairly distributed amongst the nodesand can provide maximum throughput for best effort traffic.

It should be noted that the available timeslots for best effort trafficare those remaining timeslots that are not reserved for reliabletransmission traffic. In one embodiment, in order to avoid a situationwhere best effort traffic has zero timeslots, each superframe maintainsa minimum number of timeslots that are reserved for best effort traffic.

The reliable traffic module 276 is configured to handle traffic withcertain throughput requirements, i.e., data flows with QoS and trafficspecifications. For these types of high priority data flows, end-to-endadmission control is employed by the reliable traffic module 276 toprovide end-to-end resource reservation at a level that will meet theQoS specification. Because end-to-end transmission relies on anestablished routing path, the routing path module is employed toidentify the end-to-end routing path for the reliable transmissiontraffic flow. The reliable traffic module 276 operates based on the useof layer-2 routing for packet delivery. If layer-3 routing is used forpacket delivery, then the resources that are reserved on the variousend-to-end links between nodes in the network may not be used since thelayer-3 routing may select an alternative path for delivery of thepackets. Thus, to provide QoS support, the reliable traffic moduleincorporates both routing and timeslot allocation into the sameprocedure of end-to-end admission control.

In one embodiment, when a UWB mesh node detects the arrival of a newconnection, it first determines the QoS and reliable trafficspecification of this connection. Next, the end-to-end admission controlprocess is triggered and includes determining the sequence of nodes inthe path (e.g., performed by the routing module 272), reservingtimeslots for delivery of packets at each node, and sending areservation failure message from any node or sending a reservationsuccess message from the end node.

For example, the node initiating the admission control process, firstmaps the QoS and traffic specification onto the number of requiredtimeslots and determines if there are enough available timeslots. Ifthere are, then the routing path module 272 determines which link shouldbe used for sending the data by considering the minimum hop count to thedestination. Once the link is determined, the number of requiredtimeslots is allocated to this link (if any reallocation is needed). Allneighbor nodes within two hops are then informed of the timeslotallocation to prevent interference.

This process continues at each node in the routing path until sufficientresources have been allocated at each node in the path to the end node.If any node along the path is unable to allocate the required number oftimeslots, that node sends a reservation failure message back to theinitiating node. The reservation failure message is also passed along toneighbor nodes within two hops so that they can update the status of anypreviously allocated timeslots along the reserved path as unallocated.When the reservation failure message reaches the initiating node, thatnode can inform the higher layer protocol or application protocol thatthe connection failed due to insufficient resources. Alternatively, ifreservation is successful from end-to-end, the end node sends areservation success message back to the initiating node so that thereliable transmission of data may begin.

Accordingly, the reliable traffic module 274 in cooperation with therouting path module 272 establishes an end-to-end routing path and indoing so also allocates sufficient timeslots on each link. Furthermore,this process is carried out in a distributed fashion that does notrequire coordination of all nodes in the network. This is different fromthe previously described fair resource allocation for best efforttraffic, where timeslot allocation and/or adjustment is coordinatedamong all nodes in the network. Thus, the difference between fairresource allocation for best effort traffic and end-to-end reservationfor reliable traffic delivery is that the connection setup for reliabletraffic is performed based on remaining timeslots while the resourceallocation/adjustment for best effort traffic is performed byreassignment of timeslots allocated for best effort traffic among allnodes in the interference range (e.g., two hops).

In one embodiment, when a connection is no longer needed, a teardownprocess can be started from either end node. The teardown process may beimplemented by sending a reservation release message from one end nodeall the way to the other end node following the established routingpath. Each node in the path thereby releases the reserved timeslots forthe connection and informs their respective neighbors so that thereserved timeslots are released across the network.

FIG. 10 is a flow diagram illustrating an example process forinitializing communications in a wireless network according to anembodiment of the present invention. The illustrated process may becarried out by a wireless node in a UWB network, for example the nodespreviously described in FIGS. 1, 2, 3, and 6. Initially, in step 275 thenode identifies its neighbor nodes. This can be accomplished byreceiving and analyzing beacon signals during the beacon period. Forthose nodes with sufficiently high signal quality, in step 280 the nodeestablishes a high transmission reliable link with each identifiedneighbor node. Next, in step 285 the node achieves synchronization withthe other nodes in the network. This synchronization aligns thesuperframe of the node with the superframes of the other nodes in thenetwork and aligns the respective beacon periods, contention avoidanceperiods, and contention free periods. Finally, in step 290 the nodeallocates its initial timeslots. This is done by determining whattimeslots have been allocated by other nodes in the network and thenreserving a calculated number of timeslots for the node—with thosetimeslots being distributed evenly throughout the CFP of the superframe.

FIG. 11 is a flow diagram illustrating an example process foridentifying the topology of a wireless network according to anembodiment of the present invention. The illustrated process may becarried out by a wireless node in a UWB network, for example the nodespreviously described in FIGS. 1, 2, 3, and 6. Initially, in step 300 thenode receives a beacon signal from another node. Next, in step 305 thenode determines who the sender of the beacon signal is and adds thatnode to the sender list, which can be stored in local data storage onthe node. Then in step 310, the node measures the link quality of thebeacon signal to determine if the link quality is sufficient for adirect link to be maintained with the node for high bandwidthcommunication (e.g., UWB communication). If the quality of the link issufficient, as determined in step 315, then the node establishes a linkwith the node and updates the neighbor list accordingly. If the qualityof the link is poor, then in step 320 the node determines to use themesh network for delivery of packets to the node that sent the beaconsignal and the neighbor list is updated accordingly.

FIG. 12 is a flow diagram illustrating an example process for allocatinginitial timeslots in a wireless network according to an embodiment ofthe present invention. The illustrated process may be carried out by awireless node in a UWB network, for example the nodes previouslydescribed in FIGS. 1, 2, 3, and 6. Initially, in step 320 the nodecollects information from its neighbors within two hops. Collecting theinformation from the two hop range rather than just the single hop rangeadvantageously allows the node to include those timeslots withininterference range in its allocation process. Next, in step 325, thenode determines what timeslots are already allocated to nodes in directcommunication range (one hope) or nodes in interference range (twohops). As a result, the node is able to identify in step 330 whattimeslots are unused. In step 335 the node then selects its initialtimeslots, making a point of distributing those timeslots as evenly aspossible throughout the contention free period. Once the timeslots havebeen selected, in step 340 the node informs its neighbors out to the twohop range about the initial timeslots it has allocated to itself.Advantageously, this communication can be sent in the next occurringinitial timeslot of the node.

FIG. 13 is a flow diagram illustrating an example process for allocatingresources for best effort wireless communication according to anembodiment of the present invention. The illustrated process may becarried out by a wireless node in a UWB network, for example the nodespreviously described in FIGS. 1, 2, 3, and 6. Initially, in step 350 thenode measures the best effort traffic load on each link and thencompares the load to the number of allocated timeslots for each link instep 355. Next, in step 360 the node adjusts the timeslots that areavailable for best effort traffic so that they are optimized in afashion that those links with the higher best effort traffic load orestimated best effort traffic load have more timeslots allocated to themthan those links with less best effort traffic load or estimated besteffort traffic load.

FIG. 14 is a flow diagram illustrating an example process for allocatingresources for reliable transmission according to an embodiment of thepresent invention. The illustrated process may be carried out by awireless node in a UWB network, for example the nodes previouslydescribed in FIGS. 1, 2, 3, and 6. Initially, in step 375, the nodedetects a new connection or a new traffic flow request from a higherlayer in the communication stack. For example an application on thedevice may request to send a large digital image over the network orrequest to stream an audio/video file such as a movie trailer or fullfeature film over the network. For such multimedia applications,reliable transmission is desirable to ensure a level of quality that isacceptable to a user of the wireless device and wireless communicationmedium such as a UWB communication channel.

Next, in step 380 the node obtains the QoS information and trafficspecification required for the reliable transmission. This informationmay be received from the application or higher layer. In step 385 thenode then reserves the necessary resources it needs to meet the QoSlevel by allocating enough timeslots to the link that will be used tosend the traffic to the next node in the communication path between thisnode and the end node. If the resource allocation is successful, asdetermined in step 390, then the node informs its neighbors out to twohops about the reserved timeslots, as shown in step 400. If, however,the resource allocation was not successful, in step 395 the node sends areservation failure to inform the upper layer or application thatestablishing the reliable transmission path failed.

When the node successfully allocates the resources needed to meet thedesired QoS level, then in step 405 the node determines if it is thelast node in the path between the first node and the end node. If theend node has not been reached, then in step 410 the QoS information andtraffic specification information is sent to the next node in the pathand the process of resource reservation begins anew and the next node inthe path. In this fashion, all nodes in the path between the first nodeand the end node advantageously reserve the necessary resources forreliable transmission of data at the desired QoS level. Once the endnode is reached, as determined in step 405, then in step 415 the lastnode sends a reservation success message back to the first node. Uponreceipt of the reservation success message, the first node informs theupper layer or application and the reliable transmission may begin, asshown in step 420.

FIG. 15 is a flow diagram illustrating an example process for resourcereservation according to an embodiment of the present invention. Theillustrated process may be carried out by a wireless node in a UWBnetwork, for example the nodes previously described in FIGS. 1, 2, 3,and 6. The illustrated process can be used, for example, in the contextof step 385 previously described with respect to FIG. 14. Initially, instep 430 the node determines the number of timeslots that are requiredfor the transmission of the data. Next, in step 435 the node identifiesthe link over which the data will be sent. This can be accomplished bydetermining the best route to the end node, which can be calculated, forexample, based on minimum hop count. Advantageously, each link in thepath is already know to be a high quality reliable transmission channelpursuant to the topology formation process previously described withrespect to FIG. 11. Once the target link is identified, in step 440 thenode then allocates the appropriate number of timeslots to that link tocarry the traffic at the desired QoS level.

FIG. 16 is a block diagram illustrating an example wirelesscommunication device 450 that may be used in connection with variousembodiments described herein. Other wireless communication devicesand/or architectures may also be used, as will be clear to those skilledin the art.

In the illustrated embodiment, wireless communication device 450comprises an antenna system 455, a radio system 460, a baseband system465, a speaker 464, a microphone 470, a central processing unit (“CPU”)485, a data storage area 490, and a hardware interface 495. In thewireless communication device 450, radio frequency (“RF”) signals aretransmitted and received over the air by the antenna system 455 underthe management of the radio system 460.

In one embodiment, the antenna system 455 may comprise one or moreantennae and one or more multiplexors (not shown) that perform aswitching function to provide the antenna system 455 with transmit andreceive signal paths. In the receive path, received RF signals can becoupled from a multiplexor to a low noise amplifier (not shown) thatamplifies the received RF signal and sends the amplified signal to theradio system 460.

In alternative embodiments, the radio system 460 may comprise one ormore radios that are configured to communication over variousfrequencies. In one embodiment, the radio system 460 may combine ademodulator (not shown) and modulator (not shown) in one integratedcircuit (“IC”). The demodulator and modulator can also be separatecomponents. In the incoming path, the demodulator strips away the RFcarrier signal leaving a baseband receive audio signal, which is sentfrom the radio system 460 to the baseband system 465.

If the received signal contains audio information, then baseband system465 decodes the signal and converts it to an analog signal. Then thesignal is amplified and sent to the speaker 470. The baseband system 465also receives analog audio signals from the microphone 480. These analogaudio signals are converted to digital signals and encoded by thebaseband system 465. The baseband system 465 also codes the digitalsignals for transmission and generates a baseband transmit audio signalthat is routed to the modulator portion of the radio system 460. Themodulator mixes the baseband transmit audio signal with an RF carriersignal generating an RF transmit signal that is routed to the antennasystem and may pass through a power amplifier (not shown). The poweramplifier amplifies the RF transmit signal and routes it to the antennasystem 455 where the signal is switched to the antenna port fortransmission.

The baseband system 465 is also communicatively coupled with the centralprocessing unit 485. The central processing unit 485 has access to adata storage area 490. The central processing unit 485 is preferablyconfigured to execute instructions (i.e., computer programs or software)that can be stored in the data storage area 490. Computer programs canalso be received from the baseband processor 465 and stored in the datastorage area 490 or executed upon receipt. Such computer programs, whenexecuted, enable the wireless communication device 450 to perform thevarious functions of the present invention as previously described. Forexample, data storage area 490 may include various software modules (notshown) that were previously described with respect to FIGS. 6-9.

In this description, the term “computer readable medium” is used torefer to any media used to provide executable instructions (e.g.,software and computer programs) to the wireless communication device 450for execution by the central processing unit 485. Examples of thesemedia include the data storage area 490, microphone 470 (via thebaseband system 465), antenna system 455 (also via the baseband system465), and hardware interface 495. These computer readable mediums aremeans for providing executable code, programming instructions, andsoftware to the wireless communication device 450. The executable code,programming instructions, and software, when executed by the centralprocessing unit 485, preferably cause the central processing unit 485 toperform the inventive features and functions previously describedherein.

The central processing unit 485 is also preferably configured to receivenotifications from the hardware interface 495 when new devices aredetected by the hardware interface. Hardware interface 495 can be acombination electromechanical detector with controlling software thatcommunicates with the CPU 485 and interacts with new devices. Thehardware interface 495 may be a firewire port, a USB port, a Bluetoothor infrared wireless unit, or any of a variety of wired or wirelessaccess mechanisms. Examples of hardware that may be linked with thedevice 450 include data storage devices, computing devices, headphones,microphones, and the like.

FIG. 17 is a block diagram illustrating an example computer system 550that may be used in connection with various embodiments describedherein. Other computer systems and/or architectures may be used, as willbe clear to those skilled in the art.

The computer system 550 preferably includes one or more processors, suchas processor 552. Additional processors may be provided, such as anauxiliary processor to manage input/output, an auxiliary processor toperform floating point mathematical operations, a special-purposemicroprocessor having an architecture suitable for fast execution ofsignal processing algorithms (e.g., digital signal processor), a slaveprocessor subordinate to the main processing system (e.g., back-endprocessor), an additional microprocessor or controller for dual ormultiple processor systems, or a coprocessor. Such auxiliary processorsmay be discrete processors or may be integrated with the processor 552.

The processor 552 is preferably connected to a communication bus 554.The communication bus 554 may include a data channel for facilitatinginformation transfer between storage and other peripheral components ofthe computer system 550. The communication bus 554 further may provide aset of signals used for communication with the processor 552, includinga data bus, address bus, and control bus (not shown). The communicationbus 554 may comprise any standard or non-standard bus architecture suchas, for example, bus architectures compliant with industry standardarchitecture (“ISA”), extended industry standard architecture (“EISA”),Micro Channel Architecture (“MCA”), peripheral component interconnect(“PCI”) local bus, or standards promulgated by the Institute ofElectrical and Electronics Engineers (“IEEE”) including IEEE 488general-purpose interface bus (“GPIB”), IEEE 696/S-100, and the like.

Computer system 550 preferably includes a main memory 556 and may alsoinclude a secondary memory 558. The main memory 556 provides storage ofinstructions and data for programs executing on the processor 552. Themain memory 556 is typically semiconductor-based memory such as dynamicrandom access memory (“DRAM”) and/or static random access memory(“SRAM”). Other semiconductor-based memory types include, for example,synchronous dynamic random access memory (“SDRAM”), Rambus dynamicrandom access memory (“RDRAM”), ferroelectric random access memory(“FRAM”), and the like, including read only memory (“ROM”).

The secondary memory 558 may optionally include a hard disk drive 560and/or a removable storage drive 562, for example a floppy disk drive, amagnetic tape drive, a compact disc (“CD”) drive, a digital versatiledisc (“DVD”) drive, etc. The removable storage drive 562 reads fromand/or writes to a removable storage medium 564 in a well-known manner.Removable storage medium 564 may be, for example, a floppy disk,magnetic tape, CD, DVD, etc.

The removable storage medium 564 is preferably a computer readablemedium having stored thereon computer executable code (i.e., software)and/or data. The computer software or data stored on the removablestorage medium 564 is read into the computer system 550 as electricalcommunication signals 578.

In alternative embodiments, secondary memory 558 may include othersimilar means for allowing computer programs or other data orinstructions to be loaded into the computer system 550. Such means mayinclude, for example, an external storage medium 572 and an interface570. Examples of external storage medium 572 may include an externalhard disk drive or an external optical drive, or and externalmagneto-optical drive.

Other examples of secondary memory 558 may include semiconductor-basedmemory such as programmable read-only memory (“PROM”), erasableprogrammable read-only memory (“EPROM”), electrically erasable read-onlymemory (“EEPROM”), or flash memory (block oriented memory similar toEEPROM). Also included are any other removable storage units 572 andinterfaces 570, which allow software and data to be transferred from theremovable storage unit 572 to the computer system 550.

Computer system 550 may also include a communication interface 574. Thecommunication interface 574 allows software and data to be transferredbetween computer system 550 and external devices (e.g. printers),networks, or information sources. For example, computer software orexecutable code may be transferred to computer system 550 from a networkserver via communication interface 574. Examples of communicationinterface 574 include a modem, a network interface card (“NIC”), acommunications port, a PCMCIA slot and card, an infrared interface, andan IEEE 1394 fire-wire, just to name a few.

Communication interface 574 preferably implements industry promulgatedprotocol standards, such as Ethernet IEEE 802 standards, Fiber Channel,digital subscriber line (“DSL”), asynchronous digital subscriber line(“ADSL”), frame relay, asynchronous transfer mode (“ATM”), integrateddigital services network (“ISDN”), personal communications services(“PCS”), transmission control protocol/Internet protocol (“TCP/IP”),serial line Internet protocol/point to point protocol (“SLIP/PPP”), andso on, but may also implement customized or non-standard interfaceprotocols as well.

Software and data transferred via communication interface 574 aregenerally in the form of electrical communication signals 578. Thesesignals 578 are preferably provided to communication interface 574 via acommunication channel 576. Communication channel 576 carries signals 578and can be implemented using a variety of wired or wirelesscommunication means including wire or cable, fiber optics, conventionalphone line, cellular phone link, wireless data communication link, radiofrequency (RF) link, or infrared link, just to name a few.

Computer executable code (i.e., computer programs or software) is storedin the main memory 556 and/or the secondary memory 558. Computerprograms can also be received via communication interface 574 and storedin the main memory 556 and/or the secondary memory 558. Such computerprograms, when executed, enable the computer system 550 to perform thevarious functions of the present invention as previously described.

In this description, the term “computer readable medium” is used torefer to any media used to provide computer executable code (e.g.,software and computer programs) to the computer system 550. Examples ofthese media include main memory 556, secondary memory 558 (includinghard disk drive 560, removable storage medium 564, and external storagemedium 572), and any peripheral device communicatively coupled withcommunication interface 574 (including a network information server orother network device). These computer readable mediums are means forproviding executable code, programming instructions, and software to thecomputer system 550.

In an embodiment that is implemented using software, the software may bestored on a computer readable medium and loaded into computer system 550by way of removable storage drive 562, interface 570, or communicationinterface 574. In such an embodiment, the software is loaded into thecomputer system 550 in the form of electrical communication signals 578.The software, when executed by the processor 552, preferably causes theprocessor 552 to perform the inventive features and functions previouslydescribed herein.

Various embodiments may also be implemented primarily in hardware using,for example, components such as application specific integrated circuits(“ASICs”), or field programmable gate arrays (“FPGAs”). Implementationof a hardware state machine capable of performing the functionsdescribed herein will also be apparent to those skilled in the relevantart. Various embodiments may also be implemented using a combination ofboth hardware and software.

Furthermore, those of skill in the art will appreciate that the variousillustrative logical blocks, modules, circuits, and method stepsdescribed in connection with the above described figures and theembodiments disclosed herein can often be implemented as electronichardware, computer software, or combinations of both. To clearlyillustrate this interchangeability of hardware and software, variousillustrative components, blocks, modules, circuits, and steps have beendescribed above generally in terms of their functionality. Whether suchfunctionality is implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem. Skilled persons can implement the described functionality invarying ways for each particular application, but such implementationdecisions should not be interpreted as causing a departure from thescope of the invention. In addition, the grouping of functions within amodule, block, circuit or step is for ease of description. Specificfunctions or steps can be moved from one module, block or circuit toanother without departing from the invention.

Moreover, the various illustrative logical blocks, modules, and methodsdescribed in connection with the embodiments disclosed herein can beimplemented or performed with a general purpose processor, a digitalsignal processor (“DSP”), an ASIC, FPGA or other programmable logicdevice, discrete gate or transistor logic, discrete hardware components,or any combination thereof designed to perform the functions describedherein. A general-purpose processor can be a microprocessor, but in thealternative, the processor can be any processor, controller,microcontroller, or state machine. A processor can also be implementedas a combination of computing devices, for example, a combination of aDSP and a microprocessor, a plurality of microprocessors, one or moremicroprocessors in conjunction with a DSP core, or any other suchconfiguration.

Additionally, the steps of a method or algorithm described in connectionwith the embodiments disclosed herein can be embodied directly inhardware, in a software module executed by a processor, or in acombination of the two. A software module can reside in RAM memory,flash memory, ROM memory, EPROM memory, EEPROM memory, registers, harddisk, a removable disk, a CD-ROM, or any other form of storage mediumincluding a network storage medium. An exemplary storage medium can becoupled to the processor such the processor can read information from,and write information to, the storage medium. In the alternative, thestorage medium can be integral to the processor. The processor and thestorage medium can also reside in an ASIC.

The above description of the disclosed embodiments is provided to enableany person skilled in the art to make or use the invention. Variousmodifications to these embodiments will be readily apparent to thoseskilled in the art, and the generic principles described herein can beapplied to other embodiments without departing from the spirit or scopeof the invention. Thus, it is to be understood that the description anddrawings presented herein represent a presently preferred embodiment ofthe invention and are therefore representative of the subject matterwhich is broadly contemplated by the present invention. It is furtherunderstood that the scope of the present invention fully encompassesother embodiments that may become obvious to those skilled in the artand that the scope of the present invention is accordingly limited bynothing other than the appended claims.

1. A method comprising: collecting information at a node from neighbornodes located within two-hops in a wireless communication network;identifying unused timeslots based on a determination of allocatedtimeslots for communications between neighbor nodes in directcommunication; selecting interleaved timeslots as initial timeslots,wherein the selected interleaved timeslots are distributed evenlythroughout a free time period; and communicating information about theinitial timeslots to the neighbor nodes within two-hops.
 2. The methodof claim 1, wherein the information comprises timeslots within aninterference range of the node.
 3. The method of claim 1, furthercomprising measuring a best effort traffic load on each communicationlink to neighbor nodes.
 4. The method of claim 3, further comprisingoptimizing timeslots such that communication links with higher besteffort traffic load have more allocated timeslots.
 5. The method ofclaim 1, further comprising detecting a new connection from the node toa connected node.
 6. The method of claim 5, further comprising receivingquality of service information including a required quality of servicefor the new connection.
 7. The method of claim 6, further comprisingreserving necessary resources to meet the required quality of service byallocating timeslots used to send traffic to the connected node.
 8. Anapparatus comprising: a communication interface configured to receivesignals from a wireless communication network including a plurality ofnodes; a processor configured to: collect information at a node fromneighbor nodes located within two-hops in the wireless communicationnetwork; identify unused timeslots based on a determination of allocatedtimeslots for communications between neighbor nodes in directcommunication; select interleaved timeslots as initial timeslots,wherein the selected interleaved timeslots are distributed evenlythroughout a free time period; and communicate information about theinitial timeslots to the neighbor nodes within two-hops.
 9. Theapparatus of claim 8, wherein the information comprises timeslots withinan interference range of the node.
 10. The apparatus of claim 8, whereinthe processor is further configured to measure a best effort trafficload on each communication link to neighbor nodes.
 11. The apparatus ofclaim 10, wherein the processor is further configured to optimizetimeslots such that communication links with higher best effort trafficload have more allocated timeslots.
 12. The apparatus of claim 8,wherein the processor is further configured to detect a new connectionfrom the node to a connected node.
 13. The apparatus of claim 12,wherein the processor is further configured to receive quality ofservice information including a required quality of service for the newconnection.
 14. The apparatus of claim 13, wherein the processor isfurther configured to reserve necessary resources to meet the requiredquality of service by allocating timeslots used to send traffic to theconnected node.
 15. An article of manufacture including a non-transitorycomputer readable medium having instructions stored thereon that, inresponse to execution by a computing device, cause the computing deviceto perform operations comprising: collecting information at a node fromneighbor nodes located within two-hops in a wireless communicationnetwork; identifying unused timeslots based on a determination ofallocated timeslots for communications between neighbor nodes in directcommunication; selecting interleaved timeslots as initial timeslots,wherein the selected interleaved timeslots are distributed evenlythroughout a free time period; and communicating information about theinitial timeslots to the neighbor nodes within two-hops.
 16. The articleof manufacture of claim 15, wherein the information comprises timeslotswithin an interference range of the node.
 17. The article of manufactureof claim 15, the operations further comprising measuring a best efforttraffic load on each communication link to neighbor nodes.
 18. Thearticle of manufacture of claim 17, the operations further comprisingoptimizing timeslots such that communication links with higher besteffort traffic load have more allocated timeslots.
 19. The article ofmanufacture of claim 15, the operations further comprising detecting anew connection from the node to a connected node.
 20. The article ofmanufacture of claim 19, the operations further comprising receivingquality of service information including a required quality of servicefor the new connection